add build script to auto download khronos loader for android

Signed-off-by: Schmarni <marnistromer@gmail.com>

crates/bevy_openxr/examples/android/Cargo.toml

@@ -11,6 +11,10 @@ bevy_mod_openxr.path = "../.."
 bevy = { workspace = true, default-features = true }
 bevy_xr_utils.path = "../../../bevy_xr_utils"
 
+[build-dependencies]
+reqwest = { version = "0.12", features = ["blocking"] }
+zip = "2.1"
+
 
 [lib]
 name = "bevy_openxr_android"

crates/bevy_openxr/examples/android/build.rs

@@ -0,0 +1,36 @@
+use std::{env, ffi::OsString, fs, io::Read, path::Path};
+
+pub const OPENXR_VERSION: &str = "1.1.38";
+
+fn main() {
+    println!("cargo::rerun-if-changed=build.rs");
+    if env::var_os("CARGO_CFG_TARGET_OS") != Some(OsString::from("android")) {
+        return;
+    }
+    let mut resp = reqwest::blocking::get(
+        format!(
+    "https://github.com/KhronosGroup/OpenXR-SDK-Source/releases/download/release-{}/openxr_loader_for_android-{}.aar",
+    OPENXR_VERSION,OPENXR_VERSION)).unwrap();
+    if !resp.status().is_success() {
+        eprintln!("ERROR: Unable to get OpenXR loader from github release");
+        return;
+    }
+    let mut file = Vec::new();
+    resp.read_to_end(&mut file).unwrap();
+    let out_dir = env::var_os("OUT_DIR").unwrap();
+    let dest_path = Path::new(&out_dir).join("openxr_loader_android.arr");
+    fs::write(&dest_path, file).unwrap();
+    let file = fs::File::open(&dest_path).unwrap();
+
+    let mut zip_file = zip::ZipArchive::new(file).unwrap();
+    eprintln!("{:#?}", zip_file.file_names().collect::<Vec<_>>());
+    let mut loader_file = zip_file
+        .by_name("prefab/modules/openxr_loader/libs/android.arm64-v8a/libopenxr_loader.so")
+        .unwrap();
+    let mut file = Vec::new();
+    loader_file.read_to_end(&mut file).unwrap();
+    let out_dir = env::var_os("CARGO_MANIFEST_DIR").unwrap();
+    let dest_path = Path::new(&out_dir).join("./runtime_libs/arm64-v8a/libopenxr_loader.so");
+    let _ = fs::create_dir_all(dest_path.parent().unwrap());
+    fs::write(&dest_path, file).unwrap();
+}